With the development of mobile communication technology, an electronic device is used as an essential communication device for individuals. In addition, with the provision of various supplementary services, such as a camera, data communication, video replay, audio replay and messenger, schedule management, and alarm functions in addition to a voice communication function in the electronic device, the use of the electronic device has increased gradually. As the function of the electronic device is diversified and the use thereof increases, a battery becomes bigger. However, the use of the electronic device also increases, thereby decreasing the usable time of the battery.
Generally, a user prefers to use an alarm function along with various supplementary functions using the electronic device rather than a separate alarm clock. An alarm needs to be informed using sound so as for the user to know an event or schedule. However, the electronic device performing the alarm has a possibility that the battery is exhausted and the alarm function is not performed normally. Therefore, when there is a possibility that the battery is exhausted before the alarm is generated, there is a need for a method for improving reliability in performance of an alarm function.